In clojure I'd write this, if I actually needed a class for type dispatch or interface implementation for some reason.

    (s/defrecord Animal
      [name           :- String
       number-of-legs :- Integer])
    
    (def dog (map->Animal 
               {:name "dog"
                :number-of-legs 4}))

The nice thing is that I could also skip the defrecord if I just want enforcement of the shape of the data by making a similar defschema and then I'd just use plain maps.